Soil and plant (roots and leaves) PAHs analyses

The analysis of PAHs comprised of 13PAHs and followed the procedure US-EPA method 8270D. The target analytics (Table 3) were extracted by an accelerated solvent extractor, purified using a silica gel column, and detected by a gas chromatograph (7890 A, Agilent, USA) coupled with a mass spectrometer (5977B, Agilent, USA). Deuterated fluorene, Deuterated fenanthrene, Deuterated chrysene and Deuterated perylene were added to the samples prior to extraction, and were considered as internal standards for quantification of the 13 PAHs as described by the USEPA⁵⁴.

List of PAHs analysed and their abbreviations, also used in the text and figures.

The number of rings and molecular weights are also reported.

At every 20 samples were enclosed the determination of a certified reference material (Beechwood (PCP and PAH) BCR® certified Reference Material- Sigma-Aldrich, Italy) such as quality control. Blanks and matrices plus standard addition (a mixture of 13 EPA PAHs and 4 Deuterated PAHs) were quantified sporadically to determine the accuracy of the testing. Procedural blanks were quantified sporadically to evaluate the cross-contamination. In the blank controls the PAHs elements were under the limits of detection.